1. Field of the Invention
The present invention relates to sensor systems, and more specifically to detection of three-dimensional objects in space such that their positions with respect to a central site may be registered or corresponding distances may be determined.
2. Description of Related Art
Detection systems of this type may be used in a variety of ways, in particular in automotive engineering with the use of ultrasound for determination of distances in the range of a few centimeters to several meters.
Known applications include collision avoidance systems, parking space detectors, and parking assistants.
Corresponding systems for distance measurement and for detection of surroundings are already known in various embodiments from the related art.
Published German patent document DE 102005033403 A1 describes in general a method for measuring distances, e.g., by radar, lidar or acoustic waves, in which an echo transit time is measured and analyzed. To determine the echo transit time accurately, the reflected and detected signal is compared by correlation analysis with a reference signal allocated to the sent signal using a “matched filter.”
Published German patent document DE 19744185 A1 describes an ultrasonic distance measurement for a motor vehicle in which multiple ultrasonic transducers are used. Simultaneous transmission of ultrasonic pulses is used by utilizing the superpositioning and addition of corresponding wave amplitudes to achieve higher transmission powers and thus greater ranges.
Published U.K. patent document GB 2352294 A describes an ultrasonic distance measuring system for motor vehicles, in which converters are operated one after the other at different frequencies, to be able to correct interferences or obliterations, which may occur randomly at certain frequencies, by operating at other frequencies.
Published German patent document DE 19963755 A1 describes a distance measuring device for a motor vehicle, in which several distance sensors are provided which may be operated in different operating modes to improve the quality of the measurement.
Published German patent document DE 102004038496 A1 discloses a device and a method for measuring distance for a motor vehicle, measuring certain ambient conditions of the vehicle, which have an influence on signal propagation, e.g., temperature and atmospheric humidity, when using ultrasonic signals. These variables are taken into account in analysis of the echo signals.